How normal conception works
Human fertilisation is a fascinating and involved process, and looking at how the process works can help couples suffering from infertility to understand, with the aid of information from their doctor, where their specific problem lies.
Timing
Conception is most likely to occur when the couple has sexual intercourse one or two days prior to ovulation. At this time the cervical mucus is most conducive to receiving sperm, and sexual intercourse therefore provides a continuous stream of sperm at the point that the egg is released.
Sperm and Fallopian Tubes
When the man’s semen is ejaculated near to the female’s cervix, the sperm have the opportunity to penetrate the cervical mucus. Some seminal fluid will always be left behind in the vagina, and this is no cause for concern. Sperms which make it into the cervical canal are stored there, within the mucus, for approximately one or two days, after which they are discharged in order to swim steadily upwards through the womb. Soon they make it into the fallopian tubes and find the egg released either from the left or right ovary.
The Egg
The egg follicle ruptures each month in healthy women of childbearing age, at the point when it is at maximum size. When the follicle ruptures, the egg attached to the follicle is released and channelled along the fallopian tube by the fimbria.
Fertilisation
Fertilisation most commonly takes place when the egg has travelled to the ampulla of the fallopian (uterine) tube and encounters the sperm. After this happens, the fertilized ovum becomes a zygote, the first cell of the brand new organism.
Movement of the Zygote
The zygote now moves through the fallopian tube amid the folds of the tube’s lining, partly guided toward the uterus by the cilia (fronds in the lining) and also helped by the tubal muscle.
Embryo
In around five days time the zygote divides by a process called mitosis and becomes an embryo. This is a major stage in the creation of a multicellular organism: the human baby. In the uterus the embryo comes into contact with the endometrium approximately 7 days after ovulation, adhering to the wall of the uterus and commencing implantation, by which it connects to the mother and the umbilical cord is formed. Through implantation the embryo can receive the essentials that it requires to grow and progress.
Sometimes the embryo does not make it to the uterus and instead implants into the fallopian tube. This results in a tubal or ectopic pregnancy.
Human chorionic gonadotropin (HCG)
HCG is a hormone which the embryo begins to feed into the mother’s system just after conception. It runs through the female’s blood with the effect of preventing further menstruation from occurring while the embryo grows in the womb. This is the first sure sign of pregnancy.